Christine Negroni riffs on aviation and travel and whatever else inspires her to put words to page.

Sunday, June 29, 2014

Early Loss of Power Clue to MH 370's Flight into Indian Ocean

Minutes after Malaysia Flight 370 disappeared from military radar in the early morning hours of March 8, the airplane experienced a total loss of power but recovered, according to information released by the Australian Transport Safety Bureau. The Boeing 777 last seen by a primary radar return at 2:22am (Malaysia time) headed north west along the Malacca Strait, was still flying in that direction when the power loss occurred. Three minutes later the airplane sent a log-on request to the inmarsat satellite network, meaning its energy supply was back up and running.

Why the jetliner lost power is not known, but the report explains that a log-on request, indicating that the airplane has disconnected from the satellite communication network, is not common. It happens for only a few reasons;

power interruption to the satellite data unit

a loss of critical systems to the satellite data unit

software failure

a loss of the satellite link because of altitude

The team of experts from the UK, US, Boeing, inmarsat and Thales, who have been studying the scant data associated with airplane's disappearance have concluded the most likely cause was an interruption in power to the SDU.

Whatever its cause, by 2:26am, the problem had resolved itself to the extent that the airliner's in flight entertainment system requested to go back online. Passengers may appreciate movies and games, but IFE is not considered essential by any means. Still, I am told it is given a certain priority in the lengthy list of items supplied by the aircraft's electrical system.

Flight path from NTSB in ATSB report

This loss of power came at an intriguing time in the so-far incomprehensible story of the Kuala Lumpur to Beijing flight gone terribly awry, because it occurs within minutes of the plane's last known position over the water; north of Sumatra west of Thailand at its border with Malaysia. (E96.5 N6.5 on the report's graphic) At that time the plane was heading northwest.

How the plane came to do a rough 200+ degree turn and fly south is not known. Nor for that matter is it known when the plane did the turn. Based on my reading of the inmarsat pings and the computer-assisted probability formulas run by the search team and explained in the report, the window is expansive. It places the last "large" change to the aircraft's track no more specifically than happening before 3:15 am (Malaysia time) and that could mean as long as fifty minutes after the power interruption.

At inmarsat HQ in London

This is not to say that the turn didn't happen before then, only that from 3:15 until the plane ran out of fuel five hours later, there's nothing on which to rely for that information.

All of which shows how complex the calculations must be for figuring where that plane ended up in the impossibly large Indian Ocean.

What I find intriguing is that this anomaly - hey let's call it a problem - is that it is a previously undisclosed clue about what caused this plane to veer off its track and go missing and I am not alone in thinking this could be a BIG DEAL. Talking to a experienced Boeing 777 pilot about a loss of aircraft power an hour and a half into the flight, he agreed, "That's not a subtle thing, it's not subtle at all," especially considering the possibility that the power interruption could be associated with the plane's new course to the south.

Third reading of the ATSB report requires coffee

I received the ATSB's 58 page report on Thursday, but filled as it is with complex explanations and assorted graphs and formulas, it has taken me several readings to get the general gist. This is what prompts me to take another look at my earlier post reporting that the plane may have made a dramatic spiral descent into the sea.

While I based this on my interview with Martin Dolan, chief commissioner of the safety bureau and his assessment of what would happen in an asymmetrical loss of engine power due to fuel exhaustion, pilots who fly the 777 suggest even as fuel runs out on each engine separately, other mechanisms are designed to keep the plane on a wings level glide. MH 370 probably did not careen wildly into the ocean, they say.

Pre accident photo of 9M-MRO courtesy Jay Davis

"Generators that are hardwired into the airplane" will compensate for the loss of thrust if one engine quits before the second, I am told. These are "permanent magnet generators. If the engines are turning, just windmilling power is getting to the flight controls."

The difference between slamming abruptly into the sea versus a more stable plane-provided glide is significant. The glide, estimated at 100 nautical miles by the ATSB creates an "impractically large search area," while a spiral descent narrows the range to 20 miles from the point of fuel exhaustion. Given the ATSB's commitment to search sixty-thousand square kilometers in the next year, practicality rather than most-likely scenario seems to have ruled in terms of where to start searching when the hunt for MH 370 resumes in August.

Warren Truss and Martin Dolan in Canberra on Thursday

Once again, however, I'm staggered by how the slimmest of leads can blossom and it gives me hope that sooner or later, the full story of MH 370 will be known.